U.S. patent application number 11/057973 was filed with the patent office on 2005-07-14 for wireless communication apparatus and transmission power control method thereof.
This patent application is currently assigned to Matsushita Electric Industrial Co., Ltd.. Invention is credited to Ichikawa, Yasufumi.
Application Number | 20050153671 11/057973 |
Document ID | / |
Family ID | 18554465 |
Filed Date | 2005-07-14 |
United States Patent
Application |
20050153671 |
Kind Code |
A1 |
Ichikawa, Yasufumi |
July 14, 2005 |
Wireless communication apparatus and transmission power control
method thereof
Abstract
A wireless communication apparatus includes a variable power
amplifier (19) and a power amplifier (20). A variable power
amplifier control unit (24) controls the gain of the variable power
amplifier (19) for controlling transmission power of the own
apparatus. At this time, a condition change detecting unit (28)
detects changes in conditions of the own station and a counter
station. Based upon the detected condition changes, a transmission
power control bit controlling unit (26) and a transmission power
control period controlling unit (27) change a control period of a
transmission power control bit and a transmission power control
range. This transmission power control bit is inserted into a
transmission signal, then, the transmission signal is transmitted
to the counter station. The condition changes are detected based
upon reception power, transmission power, the transmission power
control bit, a change amount of control conditions, and a change
speed of the control conditions.
Inventors: |
Ichikawa, Yasufumi;
(Kanagawa, JP) |
Correspondence
Address: |
PEARNE & GORDON LLP
1801 EAST 9TH STREET
SUITE 1200
CLEVELAND
OH
44114-3108
US
|
Assignee: |
Matsushita Electric Industrial Co.,
Ltd.
Osaka
JP
|
Family ID: |
18554465 |
Appl. No.: |
11/057973 |
Filed: |
February 15, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11057973 |
Feb 15, 2005 |
|
|
|
09777044 |
Feb 5, 2001 |
|
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Current U.S.
Class: |
455/127.2 ;
455/126; 455/522; 455/69 |
Current CPC
Class: |
H04W 52/08 20130101;
H03G 3/3042 20130101; H04W 52/367 20130101; H04W 52/267 20130101;
H04W 52/36 20130101; H04W 52/20 20130101; H04W 52/60 20130101; H04W
52/265 20130101 |
Class at
Publication: |
455/127.2 ;
455/522; 455/069; 455/126 |
International
Class: |
H04B 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 7, 2000 |
JP |
2000-29167 |
Claims
What is claimed is:
1. A wireless communication apparatus having a transmission power
control function used to control transmission power of the
apparatus by employing a transmission power control bit sent from a
communication counter station to the apparatus, comprising: a
control period changing unit which dynamically changes a control
period of the transmission power control bit in response to a
transmission condition.
2. A wireless communication apparatus as claimed in claim 1,
further comprising a transmission power control range changing unit
which changes a transmission power control range corresponding to
the transmission power control bit.
3. A wireless communication apparatus as claimed in claim 1,
further comprising a condition detecting unit which detects a
condition of the apparatus and a condition of the communication
counter station, wherein said control period changing unit changes
the control period based upon the detected condition.
4. A wireless communication apparatus as claimed in claim 2,
further comprising a condition detecting unit which detects a
condition of the apparatus and a condition of the communication
counter station, wherein said control period changing unit changes
the control period based upon the detected condition, and further
wherein said transmission power control range changing unit changes
the transmission power control range based upon the detected
condition.
5. A transmission power control method for controlling transmission
power of a communication apparatus by employing a transmission
power control bit which is sent from a counter communication
station to the apparatus, comprising a step of: dynamically
changing a control period of said transmission power control bit in
response to a transmission condition.
6. A transmission power control method as claimed in claim 5,
further comprising a step of changing a transmission power control
range corresponding to said transmission power control bit.
7. A transmission power control method as claimed in claim 5,
further comprising a step of detecting a condition of the apparatus
and a condition of the communication counter station, wherein the
control period is changed based upon said detected condition.
8. A transmission power control method as claimed in claim 6,
further comprising a step of detecting a condition of the apparatus
and a condition of the communication counter station, wherein the
control period is changed based upon the detected condition, and
further wherein the transmission power control range is changed
based upon said detected condition.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a wireless communication
apparatus used in such a mobile communication system that a mobile
communication is carried out by employing a portable telephone and
the like. More specifically, the present invention is directed to a
wireless communication apparatus used in a transmitter, and a
transmission power control method executed between a mobile station
and a base station in a mobile communication system.
[0002] Conventionally, transmission power control techniques are
known in such a mobile communication system with employment of a
portable telephone and the like. That is, in this mobile
communication system, while information is transferred,
transmission power of the own mobile station is controlled in
response to a distance between a base station and the mobile
station so as to maintain constant electric power of a signal
reached to the base station. Thus, the transmission power control
techniques are capable of reducing interference occurred between
communication channels and are capable of improving frequency
utilization efficiencies.
[0003] In particular, in a CDMA (Code Division Multiple Access)
type mobile communication system using the spread spectrum
technique, corresponding to one sort of multiple access type
communication systems for multiplexing a plurality of communication
channels, a single frequency band is commonly used by a plurality
of users. As a result, there are large possibilities that a
so-called "near-far problem" may occur, namely one communication
signal having low electric power may be masked by another
communication signal having high electric power. Therefore, the
following problem may occur. That is, a communication signal of
another communication station may deteriorate as an interference
signal wave line quality of the own communication station. To solve
this problem, various transmission power control techniques have
been conventionally investigated, or considered. More specifically,
as the transmission power control systems capable of following
interference signals which are instantaneously varied, such a
transmission power control system constituted by a closed loop is
known in this technical field. In the CDMA communication system,
more specifically, the high-linearity transmission power control
with the wide dynamic range (for example, 70 to 80 dB) is strongly
required. Furthermore, the high precision of transmission power
while the high power transmission is carried out is required in the
wide-band CDMA (W-CDMA etc.) communication system in IMT-2000, so
that the transmission power control is required in higher
precision. This wide-band CDMA communication system is presently
studied as the next generation mobile communication system.
[0004] FIG. 5 is a flow chart for describing one example of the
conventional transmission power control method realized by the
closed loop. In the case that a base station is communicated with a
mobile station, the base station determines a transmission power
control bit based upon reception power of a reception signal wave
(namely, desirable signal wave) sent from the mobile station (step
S11). The base station inserts this determined transmission power
control bit into a transmission signal, and then, transmits this
resultant transmission signal to the mobile station. The mobile
station receives the signal transmitted from the base station, and
extracts the transmission power control bit from the received
signal (step S15), and then, controls a variable power amplifier
employed in the own mobile station in response to the instruction
of this transmission power control bit so as to change the
transmission power (step S16).
[0005] Similarly, the mobile station determines a transmission
power control bit based upon reception power of a reception signal
wave (namely, desirable signal wave) sent from the base station
(step S14). The mobile station inserts this determined transmission
power control bit into a transmission signal, and then, transmits
this resultant transmission signal to the base station. The base
station receives the signal transmitted from the mobile station,
and extracts the transmission power control bit from the received
signal (step S12), and then, controls a variable power amplifier
employed in the own base station in response to the instruction of
this transmission power control bit so as to change the
transmission power (step S13).
[0006] Since such a transmission power control is carried out, the
reception power in the base station and also the reception power in
the mobile station can be kept substantially constant irrespective
of locations of the mobile station.
[0007] As previously explained, in order to perform the
transmission power control in such high precision in accordance
with the conventional transmission power control method, the
transmission power control range corresponding to the value (1
unit) of the transmission power control bit is required to be
reduced. However, if the transmission power control range is
decreased, then the rapid, or sudden variation of the reception
power cannot be followed by this conventional transmission power
control method. As a result, there is such a problem that the
precision of the transmission power control operation is
deteriorated.
[0008] Also, in order that the transmission power control operation
is carried out in such high precision in accordance with the
conventional transmission power control method, the variable power
amplifier operable in the high precision is necessarily required.
Also, the variable power amplifier must be controlled in high
precision. However, in the case that such a high-precision variable
power amplification control operation is realized by employing the
high-precision variable power amplifier, the following problems may
occur. That is, the circuit scale is increased, so that the power
consumption amount thereof is increased and further, the wireless
communication apparatus becomes bulky in size, resulting in
deteriorations of portabilities thereof.
SUMMARY OF THE INVENTION
[0009] The present invention has been made to solve the
above-described problems, and therefore, has an object to provide
both a wireless communication apparatus and a transmission power
control method, while a transmission power control operation can be
carried out in high precision with employment of a simple
arrangement, and the wireless communication apparatus can be made
compact and operable under low power consumption.
[0010] A wireless communication apparatus, according to an aspect
of the present invention, is featured by such a wireless
communication apparatus having a transmission power control
function used to control transmission power of the own
communication station by employing a transmission power control bit
sent from a communication counter station to the own communication
station, comprising a control period changing unit which changes a
control period of the transmission power control bit.
[0011] Also, preferably, the wireless communication apparatus
further comprises a transmission power control range changing unit
which changes a transmission power control range corresponding to
the transmission power control bit.
[0012] Further, preferably, the wireless communication apparatus
further comprises: a condition detecting unit which detects either
a condition of the own communication station or a condition of the
communication counter station; and the control period changing unit
changes the control period based upon the detected condition.
[0013] Also, preferably, the wireless communication apparatus
further comprises: a condition detecting unit which detects either
a condition of the own communication station or a condition of the
communication counter station; the control period changing unit
changes the control period based upon the detected condition; and
the transmission power control range changing unit changes the
transmission power control range based upon the detected
condition.
[0014] Also, a wireless communication apparatus, according to
another aspect of the present invention, is featured by that in a
wireless communication apparatus equipped with first and second
power amplifiers for amplifying transmission power transmitted from
the own communication station to the communication counter station,
and having a transmission power control function used to control
the transmission power, the wireless communication apparatus
comprises: a power amplification control unit which controls a gain
of the first power amplifier; a matching unit which performs a
matching operation of a characteristic of the second power
amplifier; and a matching control unit which controls the matching
unit.
[0015] Also, preferably, the wireless communication apparatus
further comprises: a transmission power detecting unit which
detects transmission power of the own communication station; a
transmission power correcting unit which corrects the detected
transmission power in response to a communication condition of the
own communication station; and an error calculating unit which
calculates an error between said corrected transmission power and
target transmission power, wherein both the power amplification
control unit and the matching control unit execute the control
operations thereof based upon the calculated error.
[0016] Further, preferably, the wireless communication apparatus
further comprises: an error selecting unit which selects an error
occurred in an effective control section from the plurality of
errors which are calculated over a plurality of control sections;
and both the power amplification control unit and the matching
control unit execute the control operations based upon the selected
error.
[0017] Furthermore, preferably, the wireless communication
apparatus further comprises: an error averaging unit which averages
the selected error; and both the power amplification control unit
and the matching control unit execute the control operations based
upon the averaged error.
[0018] Also, preferably, the wireless communication apparatus
further comprises: a correction amount calculating unit which
calculates a correction amount based upon the error; and a
correction amount limiting unit which limits the calculated
correction amount; and both the power amplification control unit
and the matching control unit execute the control operations based
upon the limited correction amount.
[0019] A transmission power control method, according to another
aspect of the present invention, is featured by such a transmission
power control method for controlling transmission power of the own
communication station by employing a transmission power control bit
which is sent from a counter communication station to the own
communication station, comprising: control period changing step
which changes a control period of the transmission power control
bit.
[0020] Also, preferably, the transmission power control method
further comprises: a transmission power control range changing step
which changes a transmission power control range corresponding to
the transmission power control bit.
[0021] Further, preferably, the transmission power control method
further comprises: a condition detecting step which detects either
a condition of the own station or a condition of the communication
counter station; and the control period changing step changes the
control period based upon the detected condition.
[0022] Also, preferably, the transmission power control method
further comprises: a condition detecting step which detects either
a condition of the own station or a condition of the communication
counter station; and the control period changing step changes the
control period based upon the detected condition; and the
transmission power control range changing step changes the
transmission power control range based upon the detected
condition.
[0023] Also, a transmission power control method, according to a
further aspect of the present invention, is featured by such a
transmission power control method in which transmission power
transmitted from the own communication station to a counter
communication station is controlled by way of a first power
amplifier and a second power amplifier, comprising: a gain control
step which controls a gain of the first power amplifier; a matching
step which matches a characteristic of the second power amplifier
by way of a matching circuit; and a matching control step which
controls the matching circuit.
[0024] Also, preferably, the transmission power control method
further comprises: a transmission power detecting step which
detects transmission power of the own communication station; a
transmission power correcting step which corrects the detected
transmission power in response to a communication condition of the
own communication station; and an error calculating step which
calculates an error between the corrected transmission power and
target transmission power, wherein both the power amplification
control step and the matching control step execute the control
operations thereof based upon the calculated error.
[0025] Further, preferably, the transmission power control method
further comprises an error selecting step which selects an error
occurred in an effective control section from the plurality of
errors which are calculated over a plurality of control sections,
wherein both the power amplification control step and the matching
control step execute the control operations based upon the selected
error.
[0026] Furthermore, preferably, the transmission power control
method further comprises an error averaging step for averaging the
selected error, wherein both the power amplification control step
and the matching control step execute the control operations based
upon the averaged error.
[0027] Also, preferably, the transmission power control method
further comprises: a correction amount calculating step which
calculates a correction amount based upon the error; and a
correction amount limiting step which limits the calculated
correction amount, wherein both the power amplification control
step and the matching control step execute the control operations
based upon the limited correction amount.
[0028] In accordance with the present invention, when the
transmission power of the own communication station is controlled
by employing the transmission power control bit which is sent from
the counter communication station to the own communication station,
the control period of the transmission power control bit is
changed. Also, the transmission power control range corresponding
to the transmission power control bit is changed in connection with
the change of the control period. Furthermore, both the control
period and the transmission power control range are changed in
response to either the communication condition of the own
communication station or the communication condition of the counter
communication station.
[0029] As a consequence, even when the transmission power control
range is reduced so as to control the transmission power in high
precision, the transmission power can be followed also with respect
to the sudden change in the reception power, and thus, the control
precision of the transmission power can be improved. Also, in
accordance with the present invention, while such a high-precision
variable power amplification control operation with employment of
the high-precision variable power amplifier is no longer required,
the transmission power control operation can be carried out in high
precision by using the simple arrangement. As a consequence, the
apparatus construction such as the variable power amplifier can be
made compact, and furthermore, the low power consumption can be
realized.
[0030] Also, in accordance with the present invention, while the
transmission power is controlled by both the first power amplifier
and the second power amplifier, which amplify the transmission
power transmitted from the own communication station to the counter
communication station, the gain of the first power amplifier is
controlled, and also, the matching circuit for matching the
characteristic of the second power amplifier is controlled. Also,
the transmission power of the own communication station is
detected, and the detected transmission power is corrected in
accordance with the communication condition of the own station.
While the calculation is made of the error between the corrected
transmission power and the target transmission power, both the gain
and the matching circuit are controlled based upon the calculated
error. Furthermore, such an error occurred in the effective control
section is selected from a plurality of errors which are calculated
over a plurality of control sections, and then, both the gain and
the matching circuit are controlled based upon the selected error.
Furthermore, the selected errors are averaged, and then, both the
gain and the control circuit are controlled based upon the averaged
error. Moreover, while the correction amount is calculated based on
the error, the calculated correction amount is limited. Thus, both
the gain and the matching circuit are controlled based on this
limited correction amount.
[0031] As a resulting, both the gain of the variable power
amplifier functioning as the first power amplifier and also the
matching operation of the characteristic of the semi-fixed power
amplifier functioning as the second power amplifier can be
controlled, so that the transmission power control operation can be
carried out in higher precision. As a consequence, while such a
high-precision variable power amplification control operation with
employment of the high-precision variable power amplifier is no
longer required, the transmission power control operation can be
carried out in high precision by using the simple arrangement, so
that the apparatus construction such as the variable power
amplifier can be made compact, and furthermore, the low power
consumption can be realized.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a block diagram for showing an arrangement of a
major unit of a wireless communication apparatus according to an
embodiment of the present invention.
[0033] FIG. 2 is a flow chart for describing a sequential operation
of a transmission power control method.
[0034] FIG. 3 is a flow chart for describing a sequential operation
of a transmission power amplification control operation executed in
a mobile station.
[0035] FIG. 4 is a flow chart for explaining a sequential operation
of the transmission power amplification control operation executed
in the mobile station, which is continued to that of FIG. 3.
[0036] FIG. 5 is a flow chart for explaining one method of the
conventional transmission power control method by the closed
loop.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0037] Referring now to drawings, embodiments of the present
invention will be described in detail.
[0038] FIG. 1 is a block diagram for indicating an arrangement of a
major unit of a wireless communication apparatus according to an
embodiment of the present invention.
[0039] The wireless communication apparatus, according to this
embodiment, is provided in a mobile communication appliance which
constitutes, for instance, either a base station or a mobile
station of a cellular communication system. This wireless
communication apparatus power-amplifies a signal containing
transfer information, and then transmits the power-amplified signal
to a communication counter party. A transmission power control
method as described in this specification is suitably applied
especially to such a case that while a high linearity is maintained
over a wide power control range, a transmission power control
operation should be carried out in high precision, as required in
such a mobile terminal as a base station and a portable telephone
in a CDMA type mobile communication system. Moreover, it should be
understood that the wireless communication apparatus of this
embodiment may be applied not only to a mobile communication
appliance, but also other wireless communication apparatuses which
require transmission power control operations similar to the
above-described transmission power control operation.
[0040] This example represents only such an arrangement related to
the transmission power control of the wireless communication
apparatus. However, an arrangement related to other process
operations is omitted (for instance, circuits and key inputs
related to spreading, despreading, coding, decoding, telephone
calling, telephone receiving, and controlling operations are
omitted in a CDMA type portable telephone).
[0041] The wireless communication apparatus is arranged by
containing an antenna 11 for transmitting/receiving a wireless
signal, and a transmission/reception separator 12 for separating a
transmission signal from a reception signal and vice versa. As a
signal reception system, the wireless communication apparatus is
arranged by including a wireless reception unit 31, a demodulating
unit 29 for converting a reception signal into a baseband signal,
and a baseband signal processing unit 25 for performing a signal
processing operation and a signal decoding operation of a received
baseband signal. The wireless reception unit 31 is provided with a
high frequency amplifying circuit, a local oscillating circuit, an
IF signal amplifying circuit, and the like, by which a reception
signal is high-frequency-amplified, and also, this
high-frequency-amplified signal is frequency-converted into an
intermediate frequency (IF) signal.
[0042] Also, as a transmission system, this wireless communication
apparatus is arranged by containing the above-explained baseband
signal processing unit 25, a modulating unit 22, and a wireless
transmission unit 30. The baseband signal processing unit 25
executes a signal processing operation, and a signal coding
operation of a baseband signal to be transmitted. The modulating
unit 22 modulates a transmission signal and then converts the
modulated transmission signal into an IF (intermediate frequency)
signal. The wireless transmission unit 30 power-amplifies the
transmission signal, and frequency-converts the power-amplified
transmission signal into an RF-band (radio frequency band) signal.
This wireless transmission unit 30 contains a variable power
amplifier 19, a power amplifier 20, and a matching circuit 21. The
power amplifier 20 power-amplifies the transmission signal by a
semi-fixed gain. The matching circuit 21 executes matching
operations with respect to a gain, a current consumption, a noise
characteristic, and a distortion characteristic of the power
amplifier 20.
[0043] Furthermore, as a transmission power control system, the
wireless communication apparatus includes the above-explained
baseband signal processing unit 25, the variable power amplifier
19, the power amplifier 20, and the matching circuit 21, and also a
variable power amplification control unit 24, a condition change
detecting unit 28, a transmission power control bit controlling
unit 26, and a transmission power control period controlling unit
27. The variable power amplification control unit 24 (i.e., power
amplification controlling means) controls the gain of this variable
power amplifier 19 so as to perform a transmission power control
operation. The condition change detecting unit 28 (i.e., condition
change detecting means) detects a communication condition change of
a communication counter station and a communication condition
change of the own communication station from a reception signal
wave of the communication counter station outputted from the
baseband signal processing unit 25 and also a communication
condition of the own communication station. The transmission power
control bit controlling unit 26 (i.e., transmission power control
range changing means) changes a transmission power control range of
a transmission power control bit based upon the output result of
this condition change detecting unit 28. The transmission power
control period controlling unit 27 (i.e., control period changing
means) changes a transmission power control period based upon the
output result of the condition change detecting unit 28.
[0044] Also, as a transmission power amplification control system,
the wireless communication apparatus contains a transmission power
detecting unit 13, a detection power correcting unit 14, an error
calculating unit 15, an error selecting unit 16, an error averaging
unit 17, a transmission power correction amount limiting unit 18,
and a matching circuit control unit 23. The transmission power
detecting unit 13 (i.e., transmission power detecting means)
detects transmission power of a transmission signal of the own
communication station, radiated from the antenna 11. The detection
power correcting unit 14 (i.e., transmission power correcting
means) corrects the transmission power detected by this
transmission power detecting unit 13. The error calculating unit 15
(i.e., error calculating means) calculates an error between the
transmission power corrected by this detection power correcting
unit 14 and target transmission power. The error selecting unit 16
(i.e., error selecting means) selects an error of an effective
control section from a plurality of errors which are outputted from
this error calculating unit 15 over a plurality of control
sections. The error averaging unit 17 (i.e., error averaging means)
averages the selected error. The transmission power correction
amount limiting unit 18 (i.e., correction amount calculating means
and correction amount limiting means) calculates a correction
amount with respect to the target transmission power, and also
limits the calculated correction amount. The matching circuit
control unit 23 controls the matching circuit 21 based upon the
limited correction amount.
[0045] In such a case that the wireless communication apparatus
with the arrangement shown in FIG. 1 corresponds to a mobile
station, the condition change detecting unit 28 detects both a
condition change of a base station and a change of an own station
from the reception signal wave of the base station and the
communication conditions of the own station, which are outputted
from the baseband signal processing unit 25. Next, both the
transmission power control period controlling unit 27 and the
transmission power control bit controlling unit 26 change both the
transmission power control period and the transmission power
control range of the transmission power control bit based upon the
output result of the condition change detecting unit 28.
[0046] Next, the baseband signal processing unit 25 determines a
transmission power control bit based upon reception power of a
reception signal wave (desirable signal wave) received from the
base station, and then, inserts this determined transmission power
control bit into the transmission signal. The transmission signal
is modulated by the modulating unit 22, and the modulated
transmission signal is frequency-converted into an IF-band
transmission signal. Furthermore, this IF-band transmission signal
is frequency-converted into an RF-band transmission signal, and
thereafter, this RF-band transmission signal is transmitted via the
transmission/reception separator 12 from the antenna 11 to the base
station.
[0047] Also, after the transmission signal is detected by the
transmission power detecting unit 13, the detected transmission
signal is corrected by the detection power correcting unit 14, so
that an error with respect to the target transmission power is
calculated by the error calculating unit 15. The calculated error
is selected by the error selecting unit 16 and averaged by the
error averaging unit 17, and thereafter, the resultant error is
limited by the transmission power correction amount limiting unit
18 so as to constitute a correction amount with respect to the
target transmission power.
[0048] On the other hand, a signal transmitted from the base
station is received by the antenna 11, and then, this reception
signal is entered via the transmission/reception separator 12 to
the wireless reception unit 31. This reception signal is
frequency-converted into an IF-band signal by the wireless
reception unit 31, and this IF-band reception signal is converted
into a baseband signal by the demodulating unit 29. Thereafter,
this baseband signal is entered into the baseband signal processing
unit 25. The baseband signal processing unit 25 extracts the
transmission power control bit based upon the baseband signal
outputted from the demodulating unit 29, and updates the target
transmission power, and thereafter, corrects the target
transmission power in accordance with the correction amount limited
by the transmission power correction amount limiting unit 18. Then,
both the variable power amplification control unit 24 and the
matching circuit control unit 23 control the variable power
amplifier 19 and the matching circuit 21 based upon the corrected
target transmission power.
[0049] Next, a sequential operation of a transmission power control
method according to this embodiment will now be explained more in
detail. FIG. 2 is a flow chart for describing the sequential
operation of the transmission power control method.
[0050] In FIG. 2, in the case that a mobile station is communicated
with a base station, the base station determines a transmission
power control bit based upon reception power of a reception signal
wave (desirable signal wave) of the mobile station (S101) Then,
both a change in communication conditions of the own communication
station and a change in communication conditions of the counter
communication station are detected (S102), and both the control
period of the transmission power control bit and the transmission
power control range are changed based upon the changes in the
detected communication conditions (S104 and S105). Thereafter, this
transmission power control bit is inserted into the transmission
signal, and then, the resultant transmission signal is transmitted
to the mobile station. On the other hand, the mobile station
receives a signal transmitted from the base station, and extracts a
transmission power control bit from the received signal (S203).
Then, the transmission power of the own station is controlled in
response to an instruction of the extracted transmission power
control bit (S206).
[0051] Next, the mobile station detects a change in communication
conditions of the own station and also a change in communication
conditions of the communication counter station based upon the
reception signal wave of the base station and the communication
condition of the own station, which are outputted from the baseband
signal processing unit 25, namely, the reception power, the
transmission power, the transmission power control bit, the change
amount of the control condition, and the change speed (S202). The
control period of the transmission power control bit is changed in
response to this detection result (S204)
[0052] For instance, in such a case that both the change amount of
the reception power and the change speed of this reception power
are detected at the step S202, and then the larger both the
detected change amount of the reception power and the detected
change speed thereof are increased, the shorter the control period
of the transmission power control bit at the step S204 is reduced,
the rapid, or sudden variation of the reception power can be
followed. As a result, the precision of the transmission power
control operation can be improved.
[0053] In other words, in the case that the transmission power of
the base station is wanted to be suddenly controlled at the step
S204 by the mobile station, since the transmission power control
period is shortened, the following precision of the transmission
power with respect to the desirable power can be increased, whereas
when the transmission power of the base station is wanted to be
gently controlled, since the control period of the transmission
power is prolonged, the following precision of the transmission
power with respect to the desirable power can be increased. As a
result, the precision of the transmission power control operation
can be improved, as compared with the conventional method for
fixing the control period of the transmission power.
[0054] Then, the mobile station changes the transmission power
control range in response to the communication condition changes of
the own station and also of the counter station detected at the
step S202 (S205). For example, in such a case that both the change
amount of the reception power and the change speed of this
reception power are detected at the step S202, and then the larger
both the detected change amount of the reception power and the
detected change speed thereof are increased, the wider the control
range of the transmission power control bit is increased, the
rapid, or sudden variation of the reception power can be followed.
As a result, the precision of the transmission power control
operation can be improved.
[0055] In other words, in the case that the transmission power of
the base station is wanted to be rapidly controlled at the step
S205 by the mobile station, since the transmission power control
range is widened, the following precision of the transmission power
with respect to the desirable power can be increased, whereas when
the transmission power of the base station is wanted to be gently
controlled, since the control range of the transmission power is
narrowed, the following precision of the transmission power with
respect to the desirable power can be increased. As a result, the
precision of the transmission power control operation can be
improved, as compared with the conventional method for fixing the
control period of the transmission power.
[0056] As previously explained, in the case that the mobile station
wants to rapidly control the transmission power of the transmission
power, the control range of the transmission power is widened
(increased) at the step S205, and further, the control period of
the transmission power is shortened at the step S204, so that the
control section of this transmission power control range is
shortened. As a result, the mutual effect can be improved. As a
consequence, a total number of calculations executed in the base
station can be reduced, and the wireless communication apparatus
can be made simpler, and can be operated under low power
consumption.
[0057] On the other hand, in such a case that the mobile station
wants to gently control the transmission power of the transmission
power, the control range of the transmission power is similarly
narrowed (reduced) at the step S205, and further, the control
period of the transmission power is prolonged at the step S204, so
that the control section of this transmission power control range
is prolonged. As a result, the mutual effect can be improved. As a
consequence, the transmission power control resolution in the base
station can be reduced, and the wireless communication apparatus
can be made simpler, and can be operated under low power
consumption.
[0058] Next, the mobile station determines a transmission power
control bit from the reception signal wave (step S201), and inserts
the determined transmission power control bit into the transmission
signal, and thereafter, transmits the resultant transmission signal
to the base station. On the other hand, the base station receives a
signal transmitted from the mobile station and extracts the
transmission power control bit from this reception signal (S103).
In response to the instruction of the transmission power control
bit, the mobile station controls the transmission power of the own
station (S106).
[0059] It should be noted that the process operations defined at
the steps S102, S104, and S105, which are executed in the base
station, are similar to those defined at the steps S202, S204, and
S205, which are executed in the mobile station. Since these process
operations are executed in the base station, the following
precision of the transmission power with respect to the desirable
power can be increased similar to the mobile station. As a result,
the precision of the transmission power control can be
improved.
[0060] As previously explained, in accordance with this embodiment,
since both the transmission power control range and the control
period with respect to the transmission power control bit are
changed in response to the change in the communication conditions
of the own station and also the change in the communication
conditions of the counter station, the rapid variations in the
reception power can be followed even when the transmission power
control range is reduced, or narrowed so as to control the
transmission power in high precision. As a consequence, the
precision of the transmission power control operation can be
improved.
[0061] Also, in order to perform the high precision control of the
transmission power, both the high-precision variable power
amplifier and the high-precision variable power control unit are no
longer required. Also, since the required transmission power can be
minimized by improving such precision of the transmission power
control operations realized in the base station and the mobile
station, the wireless communication apparatus can be operated under
low power consumption and can be made compact.
[0062] Next, a description will now be made of a transmission power
amplification control sequential operation, while a transmission
power control operation of a mobile station is employed as an
example. FIG. 3 and FIG. 4 are flow charts for describing
transmission power amplification control sequential operations
executed in the mobile station. This amplification control of the
transmission power is repeatedly carried out. In this embodiment, a
present execution of such a transmission power amplification
control is expressed by "n=N" by employing a total time "n", and
also, a preceding execution thereof and a succeeding execution
thereof are represented as "n=N-1" and "n=N+1", respectively.
[0063] First, when the mobile station receives a signal transmitted
from the base station, this mobile station extracts a transmission
power control bit TPC [N] of the present execution (step S401), and
then, updates a target value of transmission power (target
transmission power) POW [N] of the own mobile station (step S402).
Furthermore, the mobile station corrects the target value of the
transmission power by adding the transmission power correction
amount APCL [N-1] calculated at the step S312 during the preceding
execution of the transmission power amplification control to this
target transmission power POW [N] (step S403). Thus, this corrected
target value is used as target transmission power POWA [N].
[0064] Then, the mobile station controls both the variable power
amplifier 19 and the matching circuit 21 of the power amplifier 20
in accordance with this corrected target transmission power POWA
[N] (steps S404 and S405).
[0065] At this step S405, since the mobile station controls the
matching circuit 21 of the power amplifier 20, this mobile station
is capable of varying the matching operations of the gain, the
current consumption, the noise characteristic, and the distortion
characteristic of the power amplifier 20. As a consequence, since
the mobile station controls the matching circuit 21 of the power
amplifier 20 in response to the target transmission power POWA [N],
the wireless communication apparatus can be operated under low
power consumption, as compared with such a conventional method that
the matching circuit is fixed.
[0066] For instance, when an absolute value of the target
transmission power is small, since an input voltage of the power
amplifier 20 is lowered, both the gain and the distortion
characteristic of this power amplifier 20 can be improved. The
matching circuit 21 may be controlled in such a manner that both
the margin of the gain and the distortion characteristic are
allocated to the reduction of the current consumption and the
improvement of the noise characteristic. On the other hand, when an
absolute value of the target transmission power is large, since an
input voltage of the power amplifier 20 is high, the noise
characteristic of the power amplifier 20 can be improved. The
matching circuit 21 may be controlled in such a manner that the
spared portion of the noise characteristic is allocated to both the
reduction of the current consumption and the improvement of the
distortion characteristic.
[0067] Furthermore, since the gain of the power amplifier 20 is
controlled in response to the target transmission power, the power
control range of the variable power amplifier 19 is reduced. As a
result, the variable power amplifier can be made compact, the
wireless communication apparatus can be made simple and also can be
operated under low power consumption. This control operation may be
applied not only to the amplification control of the transmission
power, but also to the amplification control of the reception
power.
[0068] Next, the mobile station detects transmission power PDET [N]
of the own station (step S406), corrects this detected transmission
power (detection power) PDET [N] in accordance with the
communication condition of the own station in a proper manner (step
S407), and then constitutes this corrected power as corrected
detection power PDETC [N]. At this step S407, the mobile station
may properly correct the detection power in response to a
temperature of the own communication station, a power supply
voltage thereof, a transmission frequency thereof, a spreading rate
of a transmission signal thereof, a code multiple number of the
transmission signal thereof, and a peak value of transmission power
thereof. As a consequence, since the mobile station corrects the
detected power PDET [N] in order to obtain constant detection power
irrespective of various changes in the temperature of the own
station, the power supply voltage thereof, the transmission
frequency thereof, the spreading rate of the transmission signal
thereof, the code multiple number of the transmission signal
thereof, and also the peak value of the transmission power thereof,
the detection precision of the transmission power can be increased,
and also the control precision of the transmission power control
operation can be increased.
[0069] Also, at a step S407, the mobile station may correct the
detected power in response to environmental changes in a proper
manner. As a result, while the apparatus is not changed also with
respect to a new environmental changing factor, since the
coefficient of the digital filter is changed, the mobile station
may correct the detection power PDET [N] in accordance with the
environmental change. Therefore, the wireless communication
apparatus can be made simple, and can be operated under low power
consumption.
[0070] Then, the mobile station calculates an electric power error
ERR [N](=POWN [N]-PDETC [N]) every control section from a
difference between the detection power PDETC [N] corrected at the
step S407 and the target power POWN [N] (step S408), and also
selects the power error ERR [N] calculated every control section
(step S409). At this step S409, the mobile station selects only
such a power error ERR [N] in an effective control section of the
detection power PDETC [N] to constitute this selected power error
as a power error ERRS [N]. As a result, since a selection is made
of the power error ERRS [N] in the data transmission section during
the high transmission power, and also the power error ERRS [N] in
the data transmission section during the DTX (Discontinuous
Transmission) control, the detection precision of the power errors
can be increased, and also the precision of the transmission power
control can be improved.
[0071] Next, the mobile station averages the power errors ERRS [N]
selected at the step S409 over the control section (step S410). At
this step S410, the mobile station calculates an average value ERRA
[N] in accordance with a move average formula shown in the
below-mentioned formula (1), or an averaging formula with
employment of a forget coefficient indicated in the below-mentioned
formula (2):
ERRA[N]=(ERRS[N]+ERRS[N-1]+, . . . , +ERRS[N-M])/(M+1) (1)
ERRA[N]=ERRS[N].times.(1-.alpha.)+ERRA[N-1].times..alpha. (2).
[0072] As previously explained, since the power errors are
averaged, the variation contained in the power errors is reduced,
so that the precision of the transmission power control operation
can be improved.
[0073] Also, in the no data transmission sections during the low
power consumption and the DTX control operation, the mobile station
may correct the transmission power of the own station by employing
the error ERRA [N] which is averaged over the control section at
the step S410, so that the precision of the transmission power
control operation can be improved.
[0074] Then, the mobile station calculates a transmission power
correction amount APC [N] by employing the error ERRA [N] averaged
at the step S410 (step S411), and then limits this transmission
power correction amount APC [N] (step S412) to set this limited
transmission power correction amount as a transmission power
correction APCL [N]. In this case, it is so assumed that the
transmission power correction amount APC [N] is equal to the error
ERRA [N]. Also, at this step S412, the mobile station limits the
transmission power correction amount in order that the control
amount per 1 control operation does not exceed a limit value DAPC
[dB]. For instance, in such a case that an absolute value of
necessary increased/decreased power per 1 control operation is 1
dB, an absolute value of allowable minimum increased/decreased
power is 0.6 dB, and also an absolute value of allowable maximum
power is 1.4 dB, the mobile station may set the limit value DAPC to
be smaller than, or equal to 0.4 dB. As explained above, since the
transmission power correction amount per 1 control is limited, the
relative precision of the transmission power control operation can
be increased, so that the precision of the transmission power
control operation can be improved.
[0075] The process operations defined at the steps S501, S502, and
S503 and executed in the transmission power control operation when
the subsequent operation (n=N+1) is executed are similar to those
defined at the steps S401, S402, and S403 and executed in the
transmission power control when the present operation (n=N) is
executed. Subsequently, since the similar process operations
defined at the steps S401 to S412 are repeatedly carried out, the
transmission power control operation is carried out. Since the
transmission power control operation is carried out in the above
manner, the precision of the transmission power control operation
can be further improved. As a result, the wireless communication
apparatus can be made simple and can be operated under low power
consumption.
[0076] As previously described, in accordance with this embodiment,
even when the transmission power control range is reduced so as to
control the transmission power in high precision, the transmission
power can be followed also with respect to the sudden change in the
reception power, and thus, the control precision of the
transmission power can be improved.
[0077] Also, while the transmission power of the own station is
detected, based upon the detected transmission power, both the gain
of the variable power amplifier functioning as the first power
amplifier and also the matching operation of the characteristic of
the semi-fixed power amplifier functioning as the second power
amplifier can be controlled, so that the transmission power control
operation can be carried out in higher precision.
[0078] Also, in accordance with this embodiment, while such a
high-precision variable power amplification control operation with
employment of the high-precision variable power amplifier is no
longer required, the transmission power control operation can be
carried out in high precision by using the simple arrangement, so
that the apparatus construction such as the variable power
amplifier can be made compact, and furthermore, the low power
consumption can be realized.
[0079] As previously described, in accordance with the present
invention, there are such effects that the transmission power
control operation can be carried out in high precision with
employment of the simple arrangement, and the wireless
communication apparatus can be operated under low power consumption
and also can be made compact.
* * * * *